The present invention relates to a repair clamp.
More particularly, the invention provides an improved pipe repair clamp. The clamp according to the invention could be used in some cases as a coupling to join two pipe ends.
Where extensions, repairs or replacements have to be carried sometimes out under field conditions it is usually much easier to use pipe clamps which do not requiring welding. Furthermore if the work is to be carried out near flammable materials welding will be prohibited, and other methods must be used.
Many prior art pipe couplings are designed to squeeze together a pair of sloping side flanges assumed to be strongly attached or integral with the pipes. Examples of this type of coupling are seen in U.S. Pat. No. 4,568,115 to Zimmerly, U.S. Pat. No. 4,722,561 to Heckethorn et al., U.S. Pat. No. 4,919,453 to Halling et al., U.S. Pat. No. 5,277,458 to Tschann, U.S. Pat. No. 5,509,702 and U.S. Pat. No. 5,645,303 to Warehime et al., and U.S. Pat. No. 5,707,089 to Fend. Pipes and other cylindrical bodies not provided with such flange can not be coupled by devices of this type.
A pipe clamp suitable for use under field conditions is a generally hollow cylindrical body provided with means for gripping and sealing the pipes inserted therein. The diameter range of a clamp or a coupling of a designated size is limited. Such limitation is satisfactory where the outer diameter of the pipeline to be serviced or extended is known in advance. However as field service workers may need to deal with pipes made according to different standards and made of various metals or plastics, prior-art pipe couplings may have limited applications.
While a full review of prior-art pipe couplings or clamps would be volumous, the state of the art can be assessed reasonably well from a review of the above, and additional, more recent US Patents.
Wilkins discloses a complex pipe coupling in U.S. Pat. No. 6,007,106 which includes a plastic seal having high resistance to various chemicals.
The present inventor has disclosed a moderate-cost coupling in U.S. Pat. No. 6,293,556 B1 which is capable of sealing pipes of two different diameters.
Wolfsdorf in U.S. Pat. No. 6,312,025 provides clamping elements to restrain axial separation of the two pipes.
In U.S. Pat. No. 6,361,082 B1 Hauki et al. discloses a pipe coupling intended for connecting plastic tubing of the type used for small diameter low pressure installations. The coupling includes an eccentric tightening arrangement.
A pipe coupling seen in U.S. Pat. No. 6,378,915 B1 to Katz is based on an outer housing, seal members and a nut-like member which is screwed to the outer housing to compress the seal members.
Provision to resist axial separation, and to effect sealing, are included in a coupling device seen in European Patent Application EP 0 974 780 A1 to Hulsebos. The device is however quite complex, and is not intended to cope with large diameter variations.
The present inventor has disclosed a band-type pipe clamp and coupling in U.S. Pat. No. 5,271,648. Clamping was effected by the use of two complementary plates 3 and 4, the band extremities extending slightly beyond the outer edges of said plates.
Anchoring of the band extremities was however found to be limited, and the band was not utilized to provide a support for the screw clamps.
Bearing in mind this state of the art, it is now one of the objects of the present invention to obviate the disadvantages of prior art pipe couplings and to provide a band-type repair clamp which has a larger diameter range than prior-art and which could also be used as a pipe coupling.
It is a further object of the present invention to provide a wide-range pipe repair clamp provided with improved fastening means.
It is yet a further object of the present invention to provide a wide-range pipe repair clamp at moderate cost by use of a simple tension band to squeeze a flexible high-friction liner against the outer surface of the pipe.
Finally it is an object of the present invention to provide a clamp where the band and the fastener means are integral.
The present invention achieves the above objects by providing a wide-range pipe repair clamp, comprising:
a) a metal clamping band to surround 3600 of said pipe, said band being extended at both ends to form a hollow shape including a flat base, a wedge-shaped section and a convex rounded section, elongated apertures being provided to allow passage for screw fasteners through said hollow shape, narrow edges of said wedge-shaped sections being in contact with each other to form a substantially triangularly shaped space between said formed ends;
b) a flexible inner sealing sleeve disposed inside said clamping band;
c) a pair of profile strips each having a major face for contacting the outer surface of said convex rounded section, and an opposite seating face for shoulder support of a plurality of screw fasteners, said strips having apertures to allow passage of said fasteners, said profile strips sliding over said convex rounded section when said fasteners are tightened or loosened to maintain said seating face perpendicular to the axes of said fasteners; and
d) said plurality of screw fasteners inserted into said apertures wherein the tightening of said screw fasteners reduces the size of said triangularly shaped space and tightens said metal clamping band to compress said flexible inner sleeve sealingly against the outer diameter of said pipes.
In a preferred embodiment of the present invention there is provided a wide-range pipe repair clamp wherein said hollow shape being formed at both ends of said band is filled with a crush-resistant material.
In a most preferred embodiment of the present invention there is provided a wide-range pipe repair clamp wherein the allowed pipe diameter variation is about 50% more than known similar clamps.
Yet further embodiments of the invention will be described hereinafter.
In U.S. Pat. No. 5,203,594 Straub describes and claims a pipe coupling which is split in a longitudinal direction and has inwardly bent end walls and a steel insert sheet of analogous design bridging the housing gap. Possibly the bent walls are intended to prevent extrusion of the flexible sleeve under pressure, but their effect is to sharply reduce diametrical flexibility. Furthermore the tightening method shown has no leverage; tightening the screws by 5 mm will tighten the band by 5 mm.
In contradistinction thereto the present invention uses a plain band without any bent-over lips visible when viewed in a longitudinal cross-section, thus easily achieving the required flexibility. Axial extrusion of the flexible inner sleeve can be prevented without providing end wallsxe2x80x94this being the subject of one of our co-pending patent applications.
It will thus be realized that the novel clamp of the present invention serves to provide an economically viable device for repairing of pipes. Larger pipe diameters are accommodated simply by using a longer steel band and larger rubber sleeve, thus the larger the pipe diameter the greater the cost advantage relative to other designs.
Review of the present specification will also make clear that the pipe clamp is not limited for effecting temporary or permanent repair of a damaged pipe but can also be used for joining pipe ends. As a free pipe end is often unavailable in such circumstances the clamp can be dismantled and fitted over the failed section to stop further leakage.
With regard to the pair of profile strips contacting the outer surface of the convex rounded section, these are shown in the drawings with multiple apertures, the strips being as long as the coupling. It will however be understood that discrete short strips or pads could be used.
The drawings show elastomer caps fitted over the screw ends. While not functionally essential, the caps improve the appearance of the coupling, make handling the coupling more pleasant, prevent inadvertent loss of the nut and washer, and protect the screw ends from possible damage.